Process of recovering terpene products from gasoline-terpene mixtures



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- In the manufacture of turpentine, pine oil and rosin by the steam and solvent process, the oil of turpentine is steamed out of the chips, and the rosin is extracted from the 5 turpentine-free chips by means of a light bydrocarbon, usually a low boiling gasoline. From the solution or mixture thus obtained the gasoline is separated by distillation, leaving therosin as a residue. The gasoline is not,

however, recovered in a pure state, but the distillate comprises a mixture of gasoline with terpenes, terpene alcohols, etc., from which the gasoline cannot be separated by ."fractional distillation because its boiling range overlaps that of the terpene compounds. The capacity of the mixture for reuse is limited, and the commercial value of theterpene products and gasoline, if separated, is substantially greater than the commercial value of the mixture. v

The object of the invention is to effect a separation, to a substantial degree, from the gasoline of the terpene products, so that they may be obtained in a relatively pure state, thereby enabling, also, the gasoline to be frequently re-used.

This object I have accomplished by a process of extraction with sulfur dioxid, one specific example of which will now be described.

400 parts by volume ofgasoline contaming terpenes, terpene alcohols, etc., are mixed, preferably with agitation, with an equal volume of liquid sulfur dioxid cooled to (say) 20 (1., whereupon two layers form. The upper layer (A), comprising 270 parts partially purified gasoline, is readily separated from the lower layer (B) comprising chiefly or wholly terpene compounds in solution in .liquid sulfur dioxid.

The upper layer (A) may be then treated in the same way with 270 parts of liquid sulfur dioxid and separated into an upper layer (C) comprising 175 parts gasoline, and a lower layer (1)) comprising 65 parts comv prising chiefly or wholly terpene compounds in solution in liquid sulfur dioxid.

That little, if any, gasoline remains in lower layers B and l) is demonstrated by the fact that if layer B is subjected to the sulfur dioxid treatment described, no separation results.

Careful determination of percentages of polymerization residue and of specific grav-. ities shows that the portions of the original mixture which were supposedly inseparable penes in the sulfur dioxid.

Application filed August a, 1927. Serial m. 211,859.

and which were soluble in the liquid sulfur dioxld possess substantially higher densities anddower unpolymerizedvalues than the original material, which in turn possesses substantially higher density and lower unpolymerized value than layer C, showing that there was substantial concentrationof the ter-- When practicing the process on a small scale,-the sulfur dioxid may be allowed to distil ofi from the SO -terpene solution at room temperature and the recovered terpene products subsequently washed with dilute alkali. In practicing the process on a. commercial scale, it is preferred to carry out the process in a closed vessel to prevent loss by escape of volatilized sulfur dioxid, the latter being separated by volatilization into receivers from which it is again liquefied for re-use.

. The specific process described is merely lllustrative. The percentage of liquid sulfur dioxid to be added to the mixture to be puri-' fied may be varied within fairly wide limits, and the desirable amount varies with the degree of contamination of the gasoline. A single treatment is suficient to recover substantial quantities of terpene products, but

one or more additional treatments may be necessary for more complete'recovery.

It should also be understood that it is not essential that the gasoline should be freed entirely of its terpene compounds in order to fit the gasoline for re-use. The degree to. which the sulfur dioxid is cooled is not vital, sp long as it is cooled suficiently low to liquefy 1 Within the term terpene products, specified in the claims, I mean to include h drocarbon soluble components of wood ot er than rosin, as for example, terpenes, terpene alco hols, etc. I v

Where in the claims ll specify a gasoline, I mean to include any equivalent low boiling hydrocarbon or mixture of hydrocarbons, such as benzine, naphtha or the like, which may beused'in the rosin-extracting process, and which is only slightly soluble in liquid sulfur dioxide.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is: 1

1. The process of efiecting a substantial separation of terpene products from a mixture thereof with a gasoline which comprises treating the mixture with liquid sulfur dioxid 3 to dissolve out terpene products and separating therefrom the lighter gasoline-containing la er.

The process of effecting a substantial separation of terpene products from a mixture thereof with a gasoline which comprises treating the mixture with liquid sulfur dioxid to dissolve out terpene products and form a lighter layer comprising partly purified gasoline and a heavier layer comprising terpene products in solution in liquid sulfur dioxid, and retreating the lighter layer with liquid sulfur dioxid as before to eflect separation from the gasoline of additional terpene products. p

3. The process of effecting a substantial separation of terpene products from a mixturethereof. with a hydrocarbon distillate which comprises treating the mixture with liquid sulphur dioxid to dissolve out terpene products and separating therefrom the lighter hydrocarbon compound layer.

In testimony of which invention, I have hereunto set my hand, at Baltimore, on this 25th day of May, 1927.

' EBENEZER EMMET REID. 

